An automated quantum chemistry-driven, experimental characterization for high PCE donor–π–acceptor NIR molecular dyes

Abstract

A readily accessible (less than four synthetic steps) dye molecule with potential properties well-beyond the current state-of-the-art for use in dye-sensitized solar cells (DSCs) is realized from extensive quantum chemical characterization of nearly 8000 stochastically-derived novel molecules. The synthesized molecule, 23ed_20b_1ea/WM3, possesses a julolidine electron donor group and promises to exhibit a 17.5% power conversion efficiency (PCE) if paired with a suitable redox shuttle based on practical performance analysis (and up to 26.8% in a tandem system). This represents a notable PCE increase for DSC technology. The stochastic quantum chemical analysis exploring molecular dyes is based on combinations of electron donors, π-bridges, and electron acceptors to create the D–π–A molecular dye design. The D–π–A dye combinations are defined via SMILES strings and converted to Cartesian coordinates. The theoretical dyes then undergo density functional theory geometry optimizations, absorption computations, and molecular orbital analyses where a least squares fitting of two functionals minimizes the error with respect to benchmark experiment. While only a small percentage of the computed, novel molecular dyes have better properties than the current best performing benchmark molecular dyes, these still represent a notable increase in potential targets for subsequent experiment as evidenced by the experimental characterization of the synthesized 23ed_20b_1ea/WM3 molecular dye.